This substance was found to contain 20 equivalents of carbon, nine of hydrogen and one of nitrogen.
Coal-gas contains more than 200 different chemical compounds, although only a few of them were known to Hofmann and his students in 1850. These are split between hydrocarbons (which include naphthalene, benzene, and toluene) and those compounds containing oxygen (the most important being phenol or carbolic acid).
Hofmann believed that, as the formula for quinine differed from that for naphthalidine by only two additional molecules of hydrogen and oxygen, it might be possible to make quinine from the existing compound just by adding water. ‘We cannot, of course, expect to induce the water to enter merely by placing it in contact,’ he wrote. ‘But a happy experiment may attain this end by the discovery of an appropriate metamorphic process.’
William Perkin was only eleven when Hofmann published this theory, and he read it only after he was admitted to the Royal College in 1853. He soon recognised the importance of the idea. ‘I was ambitious enough to want to work on this subject,’ he recalled, and was motivated further three years later by Hofmann’s chance remark that artificial quinine was now surely within their grasp. What he had not grasped was that the apparent simplicity of quinine’s constituent parts would so thoroughly conceal the hidden complexity of their architecture. The ‘happy experiment’ desired by his mentor would not be forthcoming, or at least not in the way he had anticipated.
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* On another visit Hofmann found one of his students making good use of the gas fires to cook his meals. ‘At lunch time he used to grill sausages in the empty, scoured dish of the sand-bath . . . or bake ham and eggs for him and his friends,’ Hofmann’s student Volhard recalled. ‘Hofmann had often observed the not-quite chemical-smelling scent; one day he followed it and appeared quite unannounced in the makeshift kitchen . . . He dealt with his English pupil in masterly manner. No word of reproach, but he kept him busy until the last sausage was wholly charred.’
Chapter Four
The Recipe
She said she was going to do it, and by golly, on Thursday, she did it. Because she is the first female secretary of state of Missouri, Judi Moriarty changed the color of the state manual to . . . mauve.
For those who don’t know, mauve is a delicate shade of purple.
‘I wanted a color that represents me and made a statement,’ Moriarty said when introducing the new state manual. ‘It’s in good taste, and it has a lot of beauty.’
St Louis Post-Dispatch, 1994
In the first months of 1856, Gustave Flaubert began Madame Bovary, Karl Bechstein opened his piano factory, the plans for the bell Big Ben were drawn up at a foundry in Whitechapel and Queen Victoria instituted the Victoria Cross. During the Easter holidays of that year, August Hofmann returned briefly to Germany, and William Perkin retired to his laboratory on the top floor of his home in the East End of London. Perkin’s domestic workplace contained a small table and a few shelves for bottles. He had constructed a furnace in the fireplace. There was no running water or gas supply, and the room was lit by old glass spirit lamps. It was an amateur’s laboratory, an enthusiast’s collection of stained beakers and test tubes and rudimentary chemicals. The room smelled of ammonia. The table on which he worked was stained with spillage from previous efforts, and probably of ink as well. He was surrounded by landscape paintings and early photographs, and by jugs and mugs and other domestic trinkets that were as alien to a laboratory as delicate soda crystals were to any other house in this smoky residential neighbourhood. It was an unexpected setting for one of chemistry’s most romantic and significant moments.
Looking back, Perkin adopted a rather nonchalant tone to describe his actions. ‘I was endeavouring to convert an artificial base into the natural alkaloid quinine, but my experiment, instead of yielding the colourless quinine, gave a reddish powder. With a desire to understand this particular result, a different base of more simple construction was selected, viz. aniline, and in this case obtained a perfectly black product. This was purified and dried, and when digested with spirits of wine gave the mauve dye.’
In effect, the discovery at that time of one apparently simple molecule could rarely claim such a far-reaching impact on the development of science and industry. The room in his father’s house afforded views of the ships in the London docks, and of the London and Blackwall Railway, an inspiring vision of travel and progress. But Perkin’s view of the distance held no glimpse of the future, no vision of the Lancashire factories 200 miles away which soon would reverberate with the sound of his invention.
The chemistry was simple, involving the then popular ‘additive and subtractive’ method: find a compound that looks similar to the one you are trying to create -in this case, Perkin chose allyltoluidine – and used two standard processes, distillation and oxidisation, to alter its formula by adding oxygen and removing hydrogen (in the form of water). It was a naive manoeuvre.
Most chemists, particularly those trained by Hofmann at the Royal College, would have thrown the reddish powder into a rubbish bin, and begun again. It was Perkin’s intuitive talent – an enquiring mind in an unsupervised laboratory – that led him to experiment further, and test the effect of this procedure on aniline. And it was a mark of his skill that, in analysing the crude black product that resulted, he was able to separate out the five per cent that contained his colour.
By the time Perkin found mauve, aniline had been linked with colorants and colour-producing reactions for thirty years. The liquid had first been discovered by the Prussian chemist Otto Unverdorben in 1826, one of several products isolated from the distillation of natural vegetable indigo. Some years later the chemist Friedlieb Runge obtained it from the distillation of coal-tar, and found it gave a blue colour when combined with chloride of lime. But such colours were considered to have no practical use. In the unlikely event that a scientist would have thought a particular tint might be useful in the dyeing of a woman’s dress, they would most certainly have believed such fripperies unworthy of their calling.
But Perkin was excited about his unexpected find. Chemists blundered every day; partly, that was the nature of their job. But only occasionally did their errors lead them in interesting directions. Perkin stained a silk cloth with his discovery, and did little more than admire the new shade. It was, he realised, a brilliant and lustrous colour, and he found that it did not fade with washing or prolonged exposure to light. The problem he faced was what to do with it next. ‘After showing this colouring matter to several friends, I was advised to consider the possibility of manufacturing it upon the large scale.’
One of these friends was Arthur Church, with whom Perkin discussed the seemingly insurmountable problem of making more than a small beaker of his colour. Liquid aniline was hard to obtain in quantity, and expensive; Perkin had never set foot inside a factory, and knew nothing of manufacturing chemicals outside the laboratory; and he knew no one in the textile or dyeing trades to whom he could turn for advice.
Both Perkin and Church knew that their mentor would disapprove of any schemes not directly connected with research. They resolved not to tell Hofmann about mauve when he returned from Germany, certainly not until Perkin had established its exact properties and had conducted further experiments.
For this, Perkin moved to slightly largely premises – a hut in his garden. He enlisted the help of his brother Thomas, and together they made several batches of mauve, each purer and more concentrated than the last. Through a friend of his brother, Perkin learnt the name of a highly regarded dye works in Scotland, and decided to send the owner some samples of cloth. He received a lengthy reply from a man called Robert Pullar in the middle of June, and his tone was encouraging.
